Enhanced carbon fiber interface with thermoplastics via nanostructure surface modification: Failure, morphology and wettability analysis

Improving the fiber-matrix adhesion in thermoplastic composites remains a significant challenge due to the lack of chemical bonding between thermoplastics and common reinforcing fibers. This study investigates the effectiveness of carbon fibers enhanced with nanostructure surface modification for strengthening the interfacial adhesion to thermoplastic matrices. The fiber surface was modified with graphene nanoplatelets (GNP) through a facile coating method, and the apparent interfacial shear strength (IFSS) was determined by single-fiber pullout tests. GNP-coated fiber improved IFSS by 74 % with neat high-density polyethylene (HDPE-Neat) and 28 % with maleic anhydride-grafted HDPE (HDPE-8MA), while IFSS reduced by 27 % with polyamide 6 (PA6) due to different failure mechanisms. Morphology, chemical, and wettability analysis were conducted on the nano-enhanced carbon fibers to quantitatively elucidate these findings on micro/nanoscale, combining machine learning-based image segmentation, X-ray photoelectron spectroscopy (XPS), and contact-angle measurements of intermittent beading on fibers. • Evaluated interfacial shear strength of nano-enhanced carbon fiber within thermoplastic using single fiber pullout test. • Revealed failure mechanisms and effects of nano-coating on carbon fiber in various thermoplastic matrices. • Applied convolutional neural network technique to quantify the nano-enhanced surface morphology. • Quantified the wettability of thermoplastic to fibers using fiber beading method.